The major thrust of this proposal is to delineate the biochemical and immunohistochemical properties of amyloid occurring in association with the aging process in man. We will apply methods of hemogenization and extraction of proven efficacy for primary and secondary amyloid to tissues (heart, pancreas) rich in senile amyloid. In addition, antisera, already available, to conformational amyloid fibril antigenic determinants or fibril subunit proteins, will be used to study senile amyloid in tissue sections utilizing direct immunofluorescence or immunoperoxidase techniques. Amyloid fibrils will be isolated by water solubilization and amyloid P-component by ion exchange chromatography or by its calcium-dependent ligand properties, from senile hearts and pancreases collected prospectively from autopsy material. Subunit proteins will be sought by gel filtration of isloated fractions in dissociating media, and further studies pursued by antigenic analysis with existant or induced monospecific antisera, as well as amino terminal sequencing by Edman degradation. A recently described method for enrichment of neurofibrillary tangles will be used to purify hippocampal cortex senile plaque amyloid fibrils. By these means, it will be possible to determine whether the amyloid of aging is organ-specific or derived from locally elaborated or proteolytically digested proteins. Whereas AL (primary, immunoglobulin light chain-related) and AA (secondary, nonimmunoglobulin) amyloids appear to derive from larger serum precursors (light chains, SAA), the origin of senile amyloid remains obscure. Recent work by the principal investigator and by Westermark et al, has indicated that the subunit protein of senile cardiac amyloidosis may be a unique form of amyloid with no related serum component identified to date. These studies will be expanded to include more controls from various age groups and organs.